Method for reconditioning detachable drill bits



May 23, 1939. 2,159,841

METHOD FOR RECONDITIONING DETACHABLE DRILL BITS C. E COOK '2 Sheets-Sheet 1 Filed Sept. 25, 1957 Fltbnrna C. E COOK May 23, 1939.

METHOD FOR RECONDITIONING DETACHABLE DRILL BITS Filed Sept. 23-, 1957 2 Sheets-Sheet 2 Invent-on E. Eu GD IIIK Patented May 23, 1939 METHOD FOR. RECONDITIONING DETACH- -LE DRILL BITS Charles Edward @ook, South Porcupine, Ontario, Canada, assignor to international Detachable Bits a Equipment ted, Timmins, Ontario, Qan'ada, a corporation oi Ontario, Canada Application September 23, 1937, Serial No. 185,240

2 Claims. (El. "id-ltd) My invention relates to improvements in methods for reconditioning detachable drill bits and an object of the invention is to devise an economical method of resharpening, regauging and reconditioning detachable drill bits in the drill steel sharpener of a mine steel shop without the necessity of employing special machinery such as milling machines, broaches, grinding machines or combinations of several of these-with a consequent increase in labour cost due to the fact that specially skilled labour must be used to operate such machines.

A further object, is to devise a method wherein the only operations to resharpen, regauge and recondition the detachable bits are forging operations and no machining is neeessary. Consequently there is economy in the consumption of sharpened by my of the above machines.

A still furt er object is to originate a method which will be faster than orthodox methods for the reason that tongs may be employed to handle the detachable bits.

Another object is to devise a method which will steel as no mcgfl is removed as in the case of bits efiect further economy by a saving in the heat necessary for heating the bit, and

Yet another object is to devise a method in which the cutting edges are always in substantially perfect alignment.

While my method is J applicable for reconditioning detachable bits'of other constructions, I shall describe and illustrate it with reference to the type of detachable bit having a dovetail tongue for connection to the shank as, for .instance, the detachable bit set i'orth in United States Patent No. 2,030,576 issued February 11; 1936. a

In the drawings, l w

Fig. 1 represents a side elevation of theupper and lower portions of a divided forming die for drawing out the points of the cutting edges of the detachable bit disposed therein, said die being shown with'the upper portion retracted. Fig. 2 is a similar view to Fig. 1 only showing the upper forming die portion in its lowermost position in. abutment with the lower die portion wherein it has drawn out the points of the cutting edges of the bit.

Fig. 3 is a top plan view of the lower forming die portion showing the detachable bitto be re-v conditioned disposed thereon.

Fig. 4 is a front elevation of the forming die in its closed position corresponding with Fig. 2.

- Fig. 5 is a vertical longitudinal section through a divided clamping die showing it in the closed tioned by my method.

position holding a detachable bit to be sharpened and gauged after having had the points of its cutting edges drawn out in the forming die, and also showing the sharpening dolly in elevation for effecting such operation.

Fig. 6 is a similar view to Fig. 5' only showing the dolly completing the dollying operation.

Fig. 7 is an end view of the clamping die viewed from the dolly receiving end.

Fig. 8 is a slightly enlarged end view oi" the dolly, and

Figs. 9, 10 and 11 are respectively enlarged details in side view, plan and front view of the detachable drill bit as described to be recondi- Like characters of reference indicate corresponding parts in the difierent' views oi the drawings.

in carrying out my method I first heat the detachable bit A in a standard heating furnace and then take hold of it by the tongs B. in the form of bit illustrated this is achieved by grasping the dovetail tongue 0 by the tongs. I then position the bit between thelower and upper portions 5 and 2 respectively of a divided forming die as illustrated in Fig. l. I

The upper forming die portion 5 is mounted on the reciprocable ram 3 oi a conventional drill steel sharpener and the lower forming die portion 2 is mounted on the lower die block t oi. such sharpener. The upper die portion 8 has a recess 5 extending transversely across its lower right hand corner as viewed in the drawings in which is disposed a transverse inclined bit cutting edge forming face 5, preferably serrated, and the lower die portion 2 has a similar but opposed recess 71 with a transverse inclined bit cutting edge iorxning face 9 disposed therein also preferably serrated.

The forming face 6 with the forming face i! makes an angle of approximately 90 which is substantially the angle at the point or apex of each cutting edge of the detachable bit.

With the bit A held bythe tongs Bin the posi tion illustrated in Fig. l the ram 3 of the drill steel sharpener is brought down so that the side faces of the horizontal cutting edges of the bit are struck squarely by the forming faces t and 8 and their points are drawn out as illustrated in Fig. 2.

Opposed registering vertical slots 9 and it are formed centrally in the upper and lower die portions l and 2 to accommodate the tongs and the vertical-cutting edges of the bit. When the horizontal cutting edges of the bit A have had their points drawn out the ram 3 and attached upper forming die portion i are retracted and the bit is turned about its axis at right angles. The above operation is now repeated with the result that the remaining cutting edges of the bit A have their points similarly drawn out.

By means of the tongs B the detachable bit A is now removed from the forming die and clamped between the upper and lower portions M and i2 of a clamping die. Such clamping die has its upper portion ii mounted on the reciprocable ram 3' of the drill steel sharpener and its lower portion l2 mounted on the lower die block 3 of the same. The detachable bit to be sharpened and gauged is inserted into a conical recess in the end of the clamping die formed by the opposed recesses !3 and It in the'coacting faces of the upper and lower clamping die portions 11 i and i2. Where the detachable bit to be reconditioned is provided with a dovetail tongue 0, as shown, a recess of dovetail cross-section extends inwardly axially from the conical recess and is formed by opposed recesses I5 and it in the coacting faces of the upper and lower die portions M and 52.

With the detachable bit held centrally in the recesses in the divided clamping die, I'then dolly the bit by means of a dolly ll mounted for reciprocation in the dollying attachment (not shown) of the drill steel sharpener. Such dolly ii is provided on its nose with points 3 and valleys l9 corresponding with the valleys and points of the cutting face of the bit so that the dollying operation of the dolly not only'sharpens the cutting edges of the bit but gauges them as well as-sizing the dovetail tongue correctly. This is all done automatically in one operation. It now only remains to harden the reconditioned bit when it is ready for use.

From the above description it will be apparent that I have devised a method of reconditioning detachable drill bits wherein they are resharpaisaaei ened and gauged solely by forging with an absence of any machining operations, and wherein such reconditioning may be carried out by means of dies and dollies in the conventional drill steel sharpened without having to employ any expensive machines such as those indicated above which are essential where machining operations of any character are carried out.

Although I have described and illustrated my method as applicable to a detachable bit having a dovetail tongue for connection to a shank it will be readily understood that by superficial changes in the clamping die I may carryout my method on detachable drill bits of many varied constructions.

What I claim as my invention is:

1. In a method of reconditioning detachable drill bits of the type wherein the bit is provided with the usual cutters and a dovetail tongue for connection to a shank, the step which consists in clamping the bit in a major axial end recess in a clamping die and clamping the dovetail tongue in a minor recess in the die connected to the major recess, and in one pass by a coacting dolly insertable axially into the major recess of the die forcing the metal of the bit outwardly against the wall of the major recess to resize it, forcing the metal of the dovetail tongue outwardly against the wall of the minor recess to resize such tongue and simultaneously resharpening the cutting edges of the bit. J

2. In a method of reconditioning detachable drill bits of the type wherein the bit is provided 4 with the usual cutters and a dovetail tongue for connection to a shank, the stepswhich consist in gripping the tongue of the bit to hold it in place in the recess of a die, and subjecting the bit in the recess of the die to the dollying action of a reciprocable dolly to simultaneously in one pass resharpen its cutters, resize the bit and its tongue. 

